Common-mask guided image reconstruction for enhanced four-dimensional cone-beam computed tomography

Abstract

A system for constructing images representing a 4DCT sequence of an object from a plurality of projections taken from a plurality of angles with respect to the object and at a plurality of times, first portions of the object being less static than second portions of the object. The system may comprise a processor configured to: iteratively process projections of the plurality of projections for a plurality of groups, each group comprising projections collected while the first portions of the object are in corresponding locations, with each iteration comprising: reconstructing first image portions representing the first portions of the object, the reconstructing of each first image portion of the first image portions being based on projections in a respective group of the plurality of groups; and reconstructing the second image portion, the second image portion representing the second portions of the object, based on projections in multiple groups of the plurality of groups and on the reconstructed first image portions.

The invention claimed is: 
     
       1. A system for constructing a plurality of images representing a four-dimensional computed tomography sequence of an object from a plurality of projections, the projections being taken from a plurality of angles with respect to the object and at a plurality of times, first portions of the object being less static than second portions of the object, the system comprising:
 at least one processor configured to:
 iteratively process projections of the plurality of projections for a plurality of groups, each group of the plurality of groups comprising projections collected while the first portions of the object are in corresponding locations, with each iteration comprising:
 reconstructing first image portions representing the first portions of the object, the reconstructing of each first image portion of the first image portions being based on projections in a respective group of the plurality of groups; and 
 reconstructing a second image portion, the second image portion representing the second portions of the object, based on projections in multiple groups of the plurality of groups and on the reconstructed first image portions. 
 
 
 
     
     
       2. A method for constructing a plurality of images representing a four-dimensional computed tomography sequence of an object from a plurality of projections, the projections being taken from a plurality of angles with respect to the object and at a plurality of times, first portions of the object being less static than second portions of the object, the method comprising:
 using at least one processor:
 iteratively processing projections of the plurality of projections for a plurality of groups, each group of the plurality of groups comprising projections collected while the first portions of the object are in corresponding locations, with each iteration comprising:
 reconstructing first image portions representing the first portions of the object, the reconstructing of each first image portion of the first image portions being based on projections in a respective group of the plurality of groups; and 
 reconstructing a second image portion, the second image portion representing the second portions of the object, based on projections in multiple groups of the plurality of groups and on the reconstructed first image portions. 
 
 
 
     
     
       3. A computer-readable storage medium encoded with executable instructions that, when executed by at least one processor, cause the at least one processor to perform a method for constructing a plurality of images representing a four-dimensional computed tomography sequence of an object from a plurality of projections, the projections being taken from a plurality of angles with respect to the object and at a plurality of times, first portions of the object being less static than second portions of the object, the method comprising:
 using at least one processor:
 iteratively processing projections of the plurality of projections for a plurality of groups, each group of the plurality of groups comprising projections collected while the first portions of the object are in corresponding locations, with each iteration comprising:
 reconstructing first image portions representing the first portions of the object, the reconstructing of each first image portion of the first image portions being based on projections in a respective group of the plurality of groups; and 
 reconstructing a second image portion, the second image portion representing the second portions of the object, based on projections in multiple groups of the plurality of groups and on the reconstructed first image portions. 
 
 
 
     
     
       4. The system of  claim 1 , wherein:
 each group of the plurality of groups corresponds to one or more locations of the locations. 
 
     
     
       5. The system of  claim 1 , wherein:
 each group of the plurality of groups corresponds to one or more times of the plurality of times. 
 
     
     
       6. The system of  claim 1 , wherein:
 the at least one processor is further configured to:
 compute a common-mask based on differences between a three-dimensional computed tomography volume and a four-dimensional computed tomography volume; and 
 apply the common-mask to obtain an initial solution of reconstructing the first image portions and an initial solution of reconstructing the second image portion. 
 
 
     
     
       7. The method of  claim 2 , the method further comprising:
 computing a common-mask based on differences between a three-dimensional computed tomography volume and a four-dimensional computed tomography volume; and 
 applying the common-mask to obtain an initial solution of reconstructing the first image portions and an initial solution of reconstructing the second image portion. 
 
     
     
       8. The system of  claim 1 , wherein:
 the at least one processor is further configured to:
 for each group of the plurality of groups, combine a solution of reconstructing the first image portions with a solution of reconstructing the second image portion to produce a constructed image for the group; and 
 sequence each constructed image for each group of the plurality of groups to produce a series of constructed images. 
 
 
     
     
       9. The method of  claim 2 , the method further comprising:
 for each group of the plurality of groups, combining a solution of reconstructing the first image portions with a solution of reconstructing the second image portion to produce a constructed image for the group; and 
 sequencing each constructed image for each group of the plurality of groups to produce a series of constructed images. 
 
     
     
       10. The system of  claim 1 , wherein:
 the at least one processor comprises at least one graphics processing unit for reconstructing the first image portions and reconstructing the second image portion in parallel. 
 
     
     
       11. The system of  claim 1 , wherein:
 the first image portions comprise a plurality of motion components of the plurality of images; and 
 the second image portion comprises one or more static components of the plurality of images. 
 
     
     
       12. The system of  claim 11 , wherein:
 the one or more static components comprise a common static component of the plurality of images. 
 
     
     
       13. The system of  claim 1 , wherein:
 for at least one iteration:
 reconstructing the first image portions is based on a previous solution of reconstructing the second image portion. 
 
 
     
     
       14. The system of  claim 1 , wherein:
 the at least one processor is further configured to:
 iteratively process the projections for about 60 iterations or less. 
 
 
     
     
       15. The method of  claim 2 , wherein:
 iteratively processing the projections comprising iteratively process the projections for about 60 iterations or less. 
 
     
     
       16. The system of  claim 1 , wherein:
 the four-dimensional computed tomography sequence of the object comprises a four-dimensional cone-beam computed tomography sequence of the object. 
 
     
     
       17. The method of  claim 2 , wherein:
 each group of the plurality of groups corresponds to one or more locations of the locations. 
 
     
     
       18. The computer-readable storage medium of  claim 3 , wherein:
 each group of the plurality of groups corresponds to one or more times of the plurality of times. 
 
     
     
       19. The computer-readable storage medium of  claim 3 , the method further comprising:
 computing a common-mask based on differences between a three-dimensional computed tomography volume and a four-dimensional computed tomography volume; and 
 applying the common-mask to obtain an initial solution of reconstructing the first image portions and an initial solution of reconstructing the second image portion. 
 
     
     
       20. The computer-readable storage medium of  claim 3 , the method further comprising:
 for each group of the plurality of groups, combining a solution of reconstructing the first image portions with a solution of reconstructing the second image portion to produce a constructed image for the group; and 
 sequencing each constructed image for each group of the plurality of groups to produce a series of constructed images.